Thread-controlling mechanism for sewing machines



2 Sheds-Sheet l INVENToR. 176m /ss ATTURNEX Sept, 13, 1949. w. c. VAN NEss THREAD CONTROLLING MECHANISM FOR SEWING MACHINES Filed Fb. 18, 1947 Sept I3, 1949- w. c. VAN NESS 2,482,077

THREAD CONTROLLING MECHANISM FOR SEWING MACHINES Filed Feb. 18, 1947 2 Sheets-Sheet .2

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5 Miz'am C MMA/Yams' WITNESS BY A TTRNE Y Patented Sept. 13, 1949 STATES ATENT OFFICE THREAD-CONTROLLING MECHANISM FOR S EWIN G MACHINES William C. Van Ness, Devon,

Manufacturing The Singer Conn., assignor to Company, Eliza- This invention relates to sewing machines, and more particularly to a thread-controlling mechanism for a single-thread, rotary wing-type looper, chain-stitch sewing machine primarily designed for producing relatively long stitches of the order of approximately 2 or 3 to the inch.

In sewing machines of this type, which may be referred to as basting machines, it is common practice when stitching about a corner to temporarily stop the machine and pivot the Work about the needle which has not been raised clear of the work, in order to form a sharp or acute angle in the continuous basting seam. When turning the Work about the needle, it is desirable that the position of the looper with respect to the needle be such that the thread-loop cast out by the needle during its initial ascent be entered by the advancing beak of the looper. This seizure of the needle-thread-loop by the looper-beak eliminates the possibility of twisting the needlethread about the blade of the needle to a position out of the path of travel of the looper-beak, by the manual turning of the work about the needle. However, with the looper and needle in this desirable relative position, the previous needlethread-loop which has been seized, ldistended and spread by the rotary looper is still retained by the heel of the looper and, consequently, is not yet pulled up and set tightly against the under side of the material being stitched. The subsequent proper pulling up and setting of this previous needle-thread-loop is interfered with by the manual manipulation or turning of the work and, in fact, to such an extent that the thread-loop is not suiciently reduced in size but is left loose and hanging from the under side of the Work. This malformed stitch not only is unsightly but it improperly secures the work being stitched.

It is the object of the present invention to provide an improved thread-controlling mechanism which, when actuated, will effect the proper setting of the needle-thread-loop against the under side of the fabric while the needle remains at rest in the work.

With the above and other objects in view, as will hereinafter appear, the invention comprises the devices, combinations and arrangements of parts hereinafter set forth and illustrated in the accompanying drawings of a preferred embodiment of the invention, from which the several features of the invention and the advantages attained thereby will be readily understood by those skilled in the art.

In the drawings which show by way of illustration the preferred embodiment of the invention: Fig. 1 is a front end elevation view of a sewing machine containing the present invention, with a portion of the bed-plate in vertica1 section and the looper in needle-thread-loop seizing position preparatory to raising the presser-foot and turning the work about the needle as a pivot.

Fig. 2 is a view similar to Fig. 1, but with the presser-foot raised from the work and the thread-controller thereby swung into its position of maximum thread pull-up action.

Fig. 3 is a vertical sectional view of the bed of the machine, illustrating the manner in which the needle-thread-loop is pulled oi the heel of the looper during the swinging movement of the thread-controller from the position shown in Fig, 1 to the position shown in Fig. 2.

Fig. 4 is a front end elevation view, partly in section, of the head of the sewing machine with the face-plate removed to show the location of the parts when the presser-foot is in lowered work-engaging position.

Fig. 5 is a view similar to Fig. 4, but with the presser-bar raised.

Fig. 6 represents a horizontal sectional view taken substantially along the line 6--6, Fig. 4.

Fig. 7 is a left side elevation view, partly in section, of the lower portion of the sewing machine head.

Fig. 8 represents an enlarged sectional view of the thread-controller pivotal support taken substantially along the line 8 8, Fig. 1.

Fig. 9 illustrates the under side of a fragment of material having a line of stitching in which the last stitch before the sharp turn is malformed.

Fig. l0 is a view similar to Fig. 9, but with the stitching defect corrected by using a machine fitted with the present invention.

Referring more in detail to the drawings, the invention is illustrated as applied to the chainstitch sewing machine forming the subject of the U. S. Patent No. 2,332.125, issued to S. Zonis et al., on Oct. 19, 1943. That portion of the sewing machine shown in the accompanying drawings comprises a frame including a head il overhanging a bed I2. Journaled for rotation in suitable bearings in the frame is a main-shaft I3 carrying at one end a crank M connected by a link l5 to a needle-bar IB journaled for endwise reciprocation in spaced bearing bushings l'l fastened in the head II. The needle-bar 'I6 carries at its lower end an eye-pointed threaded needle I8. Disposed to cooperate with the needle Ill in the formation of single-thread chainstitches S is a rotary looper I9, of the wingtype, which is carried in a shaft 20 journaled for rotation in a bushing 2| secured in the bed I2. The stitches S are adopted to be formed in the work W which is advanced over the usual throat-plate 22 by means of a feed-dog 23 actuated by a conventional four-motion feeding mechanism located in the bed I2.

The work W is maintained in'contact with the throat-plate 22 and feed-dog 23 by a, presserfoot 24 carried on the lower end of a presser-bar 25 journaled for endwise sliding movement in an elongated guide-bushing 26 pressed into the head II. The presser-foot 24 is yieldingly depressed into engagement with the work W by a leaf -spring 2'! which bears directly upon the upper end of the presser-bar 25. To prevent turning of the presser-bar 25 in its guide-bushing 25, the presser-bar has clamped to it adjacent its upper end a collar 28 formed with a laterally extending guidelug 23 projecting through a vertically disposed slot 35 formed in the side wall of the head II. Secured to free end oi the guide-lug 29 is the usual s'iaclr thread regulator i As is customary, the presser-foot is adapted to be raised and lowered by presser-foot lifting means controlled either by a treadle or by a hand-operated lever. The lifting means includes a horizontally disposed rock-shaft 32 (Figs, i

`and journaled in themachineehead Il', the rock-shaft having secured to one end thereof a rock-arm 33'whose free end is bent to extend through a hole provided in the upper end of a depending link 3A, At its lower end the link 34 is pivoted on a shouldered screw 35 (Fig. 7.) which is threaded into a guide-extension 35 integral with a sleeve 3l slidabiy embracing the upper end o1 the presser-bar bushing ze. Interposed between the sliding sleeve Si and the collar 28 is a spring-.member 38. From the above, it will be understood that pressure applied on the treadle (not shown) will turn the rock-shaft 32 from the position shown in Fig. e to the position shown in Fig. 5, thus causing the rock-arm 33 through the link 5t,v to raise the sleeve 3'l, compressing the spring-member 38 between the sleeve' 3l and the coliar 23 and raising the presserbar 2 5 against the action of the leaf-spring 2. Upon release of the pressure on the treadle, the leaf-spring will return thev presser-bar to its Vlowered position. in which position the presseru foot 24 engages the work W. If it is'desired to raise the presser-foot 24, and retain it in its elevated position to enable a manual rnanipulae tion of the work, as for example turning the same at a sharp angle, there is provided the usual hand-operated lever 3.9 pivoted asv at 4I) and formed with a cam-section All disposed to ens gage beneath and elevate the guide-extension 3'3 when the hand-lever 39 is raised. Obviously the raising of the guide-extension 35 of the sleeve 3l will raise the presser-bar inopposition to the leaf-spring 21, and the hand-lever 35 when in its fully raised position (Fig. 5) will retain the presser-bar in its elevated position.

As is usual in machines of the type in which the present invention is embodied, the sewing or needle-thread T enroute to the needle i5 travels from a source of supply through a xed threadguide #i2 at the top of the machine-head l l, then .to a conventional releasable tension device 43,

then beneath the slack-thread regulator 3l, then over the usual take-up disks 44 and 45, and through several thread guides 45, 4l and 45 to the needle I8. When the presser-foot 24 is raised as shown in Fig. 2, it is desirable that the needle-thread T be relieved of excess tension. To this end, the sleeve guide-extension 38 has adjustably secured thereto a plate-member 49 (Figs.

4 and 5) having a projecting releasing-cam 50 arranged to engage the usual tension-releasing pin of the tension device when the presser-foot is raised, whereby the tension disks which engage the thread are separated in the usual manner.

in the normal functioning of the stitch-forming devices, as illustrated in the previously mentioned Zonis Patent No. 2,332,125, the needle I8 descends through the work W and during its initial ascent casts out a thread-loop which is seized by the advancing beak 5I of the looper I9. the looper, as it continues to rotate, takes the seized thread-loop, expanding and twisting it in the well known manner and retaining possession Of .Said thread-loop until the needle, in producing the next stitch, has penetrated the work and entered the seized needle-loop held spread by the looper I9. During normal sewing, the seized thread-loop distended by the looper is drawn up and set by the combined action of the needle I8, looper I9 and feed-dog 23. An interruption in the sewing occurring when the needle I8 and looper I S are in the relative position shown in Fig. 1, leaves the distended thread-loop T1. about the body of the looper I9. If the presser-foot 24 is raised at this time to enable the work W to be turned about the needle I8 to form a sharp corner in the line of stitching, the relationship between the work-feeding mechanism and the stitch-forming devices is disturbed, and frequently to the extent that after sewing is again started the distended thread-loop TL which is about the looper I9 is not properly drawn up and tightly set against the under side of the work. This results in the formation of a loose stitch such as illustrated in Fig. 9, the loose stitch being indicated as 52.

To minimize the possibility of forming the above described loose stitch at a sharp angle or corner in a continuous seam, I have invented a manually operated thread-controlling means designed to draw the thread-loop off the heel of the looper and properly set the same against the under side of the work. As shown in Figs. 1 and 2, the end of the machine-head II is covered by a face-plate 53 to which the thread-guides 46 and 4l are attached. Mounted for swinging movement on a fulcrum-screw 54 passing through the face-plate 53 is a controller-arm 55 carrying at its lower end a thread-eye 56 disposed to cooperate with the vertically spaced thread-eyes 51 and 58 of the thread-guide 4l. The controller-arm 55 is adapted to be swung about the fulcrumscrew 54 by manual operation of the presser-foot lifting mechanism through the medium of a pin 59 provided on the sleeve 3l, which pin 59 extends through a clearance opening 60 (Fig. 1) in the face-plete 53 and operates in a slot 6l out into the controller-arm 55,

The operation of the thread-controller is as follows: Assuming that the machine is stitching inthe normal manner with the work W progressing in the direction of arrow A, Fig. l0, and that the point C at which the work is to be turned has been reached, the operator raises the presserfoot 24 off the work either by actuating the treadle or the hand-lever 39 after being sure that the needle I8 and the looper I9 are in the proper relative position, as shown in Fig. 1. The sleeve 31 is slidingly raised on the bushing 26 by the presser-foot lifting means and in moving up wardly the pin 59 carried thereby operates in the slot 6I of the controller-arm 55 to swing said arm upwardly from a substantially vertical or inoperative position (Fig. 1) to an inclined or operative position (Fig. 2). In swinging from inoperative position to operative position, the thread-eye 56 on the controller-arm 55 engages the needle-thread T traveling between the threadeyes 5l and 58, forming a distended bight in the needle-thread T. During the initial swinging of the controller-arm, the thread-loop Ti. which is about the looper i9 is drawn up and oli the smoothly curved heel 62 of the looper, as shown in Fig. 3. After the thread-loop T1. is clear of the heel 62 of the looper, further swinging movement of the controller-arm 55 draws the threadloop TL tightly about the needle I8 and up against the under side of the work W, as shown in Fig. 2. The thread capacity of the controller-arm 55 exceeds the length of thread forming the threadloop TL, insuring that the thread-loop Ti. is properly set against the under side of the work W. The additional thread required to satisfy the demands of the thread-controller is readily obtained from the source of supply by virtue of the fact that the tension device 43 is released by the cam 5D when the presser-foot approaches its fully elevated position. The released tension permits the thread-controller to pull the needed additional thread from the source of supply without breaking the thread.

From the above description it will be understood that the controller-arm 55 sets the stitch against the under side of the work during the raising of the presser-foot 24, and that when the beak 5l of the looper has entered the thread-loop cast out by the needle I8, the Work W can be turned about the needle as a pivot without aiecting in any way the proper formation of the next stitch in the seam. As shown in Fig. 10, the stitches at point c are tightly set and the work is thus properly secured by the stitches and the seam has a good appearance. Another advantage obtained from the use of my improved thread-controller is that at the termination of every seam the mere raising of the presser-foot 24 to permit withdrawal of the work will actuate the controller-arm 55 and thus draw from the supply a length of thread sulicient to eliminate accidental unthreading of the needle during the formation of the rst stitch in the next seaming operation.

Having thus set forth the nature of the invention. what I claim herein is:

1. In a single-thread chain-stitch sewing machine. the combination with an endwise movable thread-carrying needle, a rotary wing-type looper adapted to enchain thread-loops presented thereto by said needle, means for rotating said looper, a presser-foot, and means for raising and lowering said presser-foot, of a movable threadcontroller actuated by the raising of the presserfoot and operable when the looper has just seized the thread-loop cast out by the needle for pulling the previously seized and spread thread-loop off the looper and setting the same against the under side of the work.

2. In a single-thread chain-stitch sewing machine, the combination with an endwise movable thread-carrying needle, a rotary wing-type looper adapted to enchain thread-loops presented thereto by said needle, means for rotating said looper, e, presser-foot, and means for raising and lowering said presser-foot, of a movable threadcontroller actuated by the raising of the presserfoot and operable when the looper has just seized the thread-loop cast out by the needle for pulling the previously seized and spread thread-loop oiT the looper and setting the same against the under side of the work, said thread-controller including a movable arm operatively connected with said means for raising and lowering said presser-foot.

3. A sewing machine having, in combination, an endwise movable thread-carrying needle, a rotary wing-type looper cooperating with said needle in enchaining thread-loops presented by said needle, means for rotating said looper, a presser-foot, a presser-bar carrying said presserfoot, means for raising and lowering said presserfoot including a member movable in a direction parallel with the longitudinal axis of said presserbar, and a thread-controller including a movable arm having a thread-engaging eye, and means operatively connecting said movable arm with said member.

4. A sewing machine having, in combination, an endwise movable thread-carrying needle, a rotary wing-type looper cooperating with said needle in enchaining thread-loops presented by said needle, means for rotating said looper, a presser-foot, a presser-bar carrying said presserfoot, means for raising and lowering said presserfoot including a member movable in a direction parallel with the longitudinal axis of said presserbar, a pin projecting from said member, and a pivotally supported thread-controller arm formed with a slot disposed to be entered by the pin projecting from said member, whereby said threadcontroller arm is actuated by the raising and lowering of said presser-foot.

5. In a sewing machine having a frame provided with a head, an endwise reciprocatory needle-bar journaled in said head, a threaded needle carried by said needle-bar, a looper cooperating with said needle in the formation of stitches, means for actuating said looper, a presser-foot, a presser-bar journaled for endwise sliding movement in said head, means for raising and lowering said presserfoot and including a member movable in a direction parallel with the longitudinal axis of said presser-bar, a thread-controlling arm mounted for swinging movement about an aXis substantially normal to the line of movement of said presser-bar, and means operatively connecting said thread-controlling arm with said member.

6. In a sewing machine having a frame provided with a head, a face-plate secured to said head and having a clearance opening formed therein, an endwise reciprocatory needle-bar journaled in said head, a threaded needle carried by said needle-bar, a, looper cooperating with said needle in the formation of stitches, means for actuating said looper, a presser-foot, a presser-bar journaled for endwise sliding movement in said head, means for raising and lowering said presserfoot and including a movable member having a projection extending through the clearance opening in said face-plate, and a thread-controlling arm mounted on said face-plate for swinging movement about an axis substantially normal to the line of movement of said presser-bar, said thread-controlling arm being operatively connected to said projection.

WILLIAM C. VAN NESS.

REFERENCES CITED The following references are of le of this patent:

UNITED STATES PATENTS record in the 

